lkml.org 
[lkml]   [2018]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 09/20] signal: Pass pid and pid type into send_sigqueue
Make the code more maintainable by performing more of the signal
related work in send_sigqueue.

A quick inspection of do_timer_create will show that this code path
does not lookup a thread group by a thread's pid. Making it safe
to find the task pointed to by it_pid with "pid_task(it_pid, type)";

This supports the changes needed in fork to tell if a signal was sent
to a single process or a group of processes.

Having the pid to task transition in signal.c will also make it easier
to sort out races with de_thread and and the thread group leader
exiting when it comes time to address that.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
include/linux/sched/signal.h | 2 +-
kernel/signal.c | 14 +++++++++-----
kernel/time/posix-timers.c | 13 ++++---------
3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index ee30a5ba475f..94558ffa82ab 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -330,7 +330,7 @@ extern int send_sig(int, struct task_struct *, int);
extern int zap_other_threads(struct task_struct *p);
extern struct sigqueue *sigqueue_alloc(void);
extern void sigqueue_free(struct sigqueue *);
-extern int send_sigqueue(struct sigqueue *, struct task_struct *, int group);
+extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);

static inline int restart_syscall(void)
diff --git a/kernel/signal.c b/kernel/signal.c
index 8d8a940422a8..40feb14e276d 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1664,17 +1664,20 @@ void sigqueue_free(struct sigqueue *q)
__sigqueue_free(q);
}

-int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
+int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
{
int sig = q->info.si_signo;
struct sigpending *pending;
+ struct task_struct *t;
unsigned long flags;
int ret, result;

BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));

ret = -1;
- if (!likely(lock_task_sighand(t, &flags)))
+ rcu_read_lock();
+ t = pid_task(pid, type);
+ if (!t || !likely(lock_task_sighand(t, &flags)))
goto ret;

ret = 1; /* the signal is ignored */
@@ -1696,15 +1699,16 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
q->info.si_overrun = 0;

signalfd_notify(t, sig);
- pending = group ? &t->signal->shared_pending : &t->pending;
+ pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
list_add_tail(&q->list, &pending->list);
sigaddset(&pending->signal, sig);
- complete_signal(sig, t, group);
+ complete_signal(sig, t, type != PIDTYPE_PID);
result = TRACE_SIGNAL_DELIVERED;
out:
- trace_signal_generate(sig, &q->info, t, group, result);
+ trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
unlock_task_sighand(t, &flags);
ret:
+ rcu_read_unlock();
return ret;
}

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 2bdf08a2bae9..2d2e739fbc57 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -332,8 +332,8 @@ void posixtimer_rearm(struct siginfo *info)

int posix_timer_event(struct k_itimer *timr, int si_private)
{
- struct task_struct *task;
- int shared, ret = -1;
+ enum pid_type type;
+ int ret = -1;
/*
* FIXME: if ->sigq is queued we can race with
* dequeue_signal()->posixtimer_rearm().
@@ -347,13 +347,8 @@ int posix_timer_event(struct k_itimer *timr, int si_private)
*/
timr->sigq->info.si_sys_private = si_private;

- rcu_read_lock();
- task = pid_task(timr->it_pid, PIDTYPE_PID);
- if (task) {
- shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
- ret = send_sigqueue(timr->sigq, task, shared);
- }
- rcu_read_unlock();
+ type = !(timr->it_sigev_notify & SIGEV_THREAD_ID) ? PIDTYPE_TGID : PIDTYPE_PID;
+ ret = send_sigqueue(timr->sigq, timr->it_pid, type);
/* If we failed to send the signal the timer stops. */
return ret > 0;
}
--
2.17.1
\
 
 \ /
  Last update: 2018-07-24 05:26    [W:0.327 / U:9.800 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site